Food packaging film, and gift-boxed small roll of food packaging film

ABSTRACT

The present invention provides a food wrapping film containing a thermoplastic resin, a blue colorant, and a polyglycerol fatty acid ester.

TECHNICAL FIELD

The present invention relates to a food wrapping film and an articlethat is a food wrapping rolled film with a box.

BACKGROUND ART

Conventionally, food wrapping films have been widely used commerciallyin hotels, restaurants, and other such establishments, as well as in thehome, during food storage, preparation, and the like. In recent years, afood wrapping film having a thermoplastic resin as a main component andfurther containing a colorant, such as a copper phthalocyanine colorant,has been proposed to make it easier to see visually whether a piece ofthe film has become mixed in the food (Patent Literature 1).

On the other hand, it is common to add an anti-fogging agent to the foodwrapping film to prevent moisture in the food from adhering to the filmas water droplets.

CITATION LIST Patent Literature

[Patent Literature 1] Japanese Unexamined Patent Publication No.2015-7198

SUMMARY OF INVENTION Technical Problem

According to investigations by the present inventors, it has been foundthat when a blue colorant is used together with an anti-fogging agent,the blue colorant does not uniformly disperse in the film, and thecoloring of the film tends to become uneven.

Therefore, it is an object of the present invention to provide a foodwrapping film having excellent dispersibility of the blue colorant, andan article that is a food wrapping rolled film with a box.

Solution to Problem

The present invention provides a food wrapping film containing athermoplastic resin, a blue colorant, and a polyglycerol fatty acidester.

The content of the polyglycerol fatty acid ester is preferably 0.5% bymass or more based on the total amount of the film.

The thermoplastic resin may be at least one selected from the groupconsisting of polyvinyl chloride resins, polyvinylidene chloride resins,polyolefin resins, polystyrene resins, polyester resins and polyamideresins.

The film may contain, as the thermoplastic resin, 70% by mass or morebased on the total amount of the film of at least one resin selectedfrom the group consisting of polyvinyl chloride resins, polyvinylidenechloride resins and polyolefin resins.

The present invention also provides an article including the foodwrapping film, a core material on which the food wrapping film isrolled, and a box in which the food wrapping film and the core materialare stored, wherein the box is provided with a blade part for cuttingthe food wrapping film.

Advantageous Effects of Invention

According to the present invention, it is possible to provide a foodwrapping film that has excellent dispersibility of the blue colorant andan article that is a food wrapping rolled film with a box.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view showing a food wrapping rolled film with abox.

DESCRIPTION OF EMBODIMENTS

The film according to the present embodiment contains a thermoplasticresin, a blue colorant, and a polyglycerol fatty acid ester, and ispreferably used as a food wrapping film.

The thermoplastic resin may be a polyvinyl chloride resin such aspolyvinyl chloride; a polyvinylidene chloride resin such aspolyvinylidene chloride; a polyolefin resin such as polyethylene,polypropylene or saponified ethylene-vinyl acetate copolymer; apolystyrene resin such as butadiene-styrene copolymer,acrylonitrile-styrene copolymer, polystyrene, styrene-butadiene-styrenecopolymer, styrene-isoprene-styrene copolymer or styrene-acrylic acidcopolymer; a polyester resin such as polyethylene terephthalate,polyethylene naphthalate or polybutylene terephthalate; a polyamideresin such as 6-nylon, 6,6-nylon or 12-nylon; or the like. Thethermoplastic resin is preferably a polyvinyl chloride resin, apolyvinylidene chloride resin or a polyolefin resin, and more preferablya polyvinyl chloride resin, a polyvinylidene chloride resin or apolyethylene resin, from the viewpoint of excellent handling property.The thermoplastic resin is preferably a polyvinyl chloride resin fromthe viewpoint of excellent dispersibility of the blue colorant.

As the polyvinyl chloride resin, a polyvinyl chloride resin having anaverage degree of polymerization of 700 to 1300 is preferable from theviewpoint of excellent moldability, heat resistance and fluidity of thefilm. The average polymerization degree in the present specificationmeans an average degree of polymerization measured according to JISK6720-2.

The polyvinyl chloride resin may be a vinyl chloride homopolymer(polyvinyl chloride resin) from the viewpoint of excellent mechanicalproperties, or the polyvinyl chloride resin may be a copolymer of avinyl chloride and other monomer copolymerizable therewith, for thepurpose of imparting other properties. The copolymer may be a graftcopolymer, a block copolymer or a random copolymer. Examples of theother monomer include olefins such as ethylene, propylene andpolybutene; vinyl esters of saturated acids such as vinyl acetate andvinyl laurate; alkyl esters of unsaturated acids such as methyl acrylateand methyl methacrylate; alkyl vinyl ethers such as lauryl vinyl ether;maleic acid, acrylonitrile, styrene, methylstyrene, vinylidene fluoride;and the like. When the polyvinyl chloride resin is a copolymer, thecontent of the vinyl chloride unit in the copolymer may be 10% by massor more based on the total amount of monomer units, and is preferably30% by mass or more and more preferably 50% by mass or more, from theviewpoint of excellent mechanical properties. The upper limit of thecontent of the vinyl chloride unit in the copolymer is not particularlylimited, and may be, for example, 99% by mass or less based on the totalamount of monomer units.

The polyvinyl chloride resin may be, for example, a polymer blend with athree-dimensional polymer of acrylonitrile-butadiene-styrene or thelike, a post-treatment product with an alcohol or the like, or apost-treatment product with a chlorine-containing compound. In thesecases, the content of the vinyl chloride unit in the polyvinyl chlorideresin may be 10% by mass or more based on the total amount of the resin.

The polyvinylidene chloride resin may be a vinylidene chloridehomopolymer (polyvinylidene chloride resin), for example, may be acopolymer containing vinylidene chloride and other monomercopolymerizable with vinylidene chloride as monomer units. The othermonomer may be vinyl chloride, an acrylate ester of acrylic acid and analcohol having 1 to 8 carbon atoms, a methacrylic acid ester ofmethacrylic acid and an alcohol having 1 to 8 carbon atoms, a vinylester of an aliphatic carboxylic acid, an unsaturated aliphaticcarboxylic acid, an olefin, a vinyl ether, or the like. The copolymer ofvinylidene chloride and vinyl chloride shall belong to thepolyvinylidene chloride resin.

The content of the vinylidene chloride unit in the polyvinylidenechloride resin may be, for example, 60% by mass or more, 70% by mass ormore, or 80% by mass or more, based on the total amount of monomerunits, from the viewpoint of moldability and heat resistance of thefilm. The upper limit of the content of the vinylidene chloride unit inthe polyvinylidene chloride resin is not particularly limited, and maybe, for example, 99% by mass or less based on the total amount ofmonomer units. The content of the vinylidene chloride unit can bemeasured by a nuclear magnetic resonance (NMR) apparatus.

The weight average molecular weight of the polyvinylidene chloride resinmay be, for example, 40,000 to 180,000, 60,000 to 160,000, or 80,000 to140,000. The weight average molecular weight of the polyvinylidenechloride resin can be measured by GPC method using polystyrene of knownmolecular weight as a standard substance.

The conditions of the GPC method used for measuring the weight averagemolecular weight of the polyvinylidene chloride resin are as follows. Agel chromatograph Alliance GPC 2000 model manufactured by WatersCorporation is used as a measuring device. A solution prepared bydissolving a polyvinylidene chloride resin in tetrahydrofuran so as tobe 0.5% by weight is used as a sample.

Column: TSKgel GMHHR-H(S) HT 30 cm×2, TSKgel GMH6-HTL 30 cm×2manufactured by Tosoh Corporation

Mobile phase: Tetrahydrofuran

Detector: Differential refractometer

Flow rate: 1.0 mL/min

Column temperature: 20° C.

Injection amount: 500 μL

When the thermoplastic resin is a polyvinyl chloride resin or apolyvinylidene chloride resin, the film may further contain aplasticizer. Examples of the plasticizer include epoxidized oils such asepoxidized linseed oil, epoxidized soybean oil and epoxidized fatty acidalkyl ester, adipic acid esters having a linear or branched alkyl grouphaving 6 to 10 carbon atoms, hydroxy polycarboxylic acid esters such astributyl acetylcitrate and triethyl acetylate, fatty acid group dibasicacid esters such as di-normal butyl sebacate, glycol esters such aspentaerythritol ester and diethylene glycol benzoate, phosphate esterssuch as triphenyl phosphate and tricresyl phosphate, glycerindiacetomonolaurate, chlorinated paraffin, polyester plasticizers, andthe like. These plasticizers are used singly or in combination of two ormore. The content of the plasticizer is appropriately adjusted withinthe range of, for example, 20 to 50 parts by mass, based on 100 parts bymass of the polyvinyl chloride resin, depending on application such asthe type of food to be wrapped, wrapping form, and wrapping method.

Examples of the polyolefin resin include polyethylene resins and thelike, and the polyethylene resin may be a copolymer using low densitypolyethylene, linear low density polyethylene, linear ultra low densitypolyethylene, medium density polyethylene, high density polyethylene,ethylene or the like, as monomer units. Specifically, the polyethyleneresin is a copolymer of ethylene and one or more selected from a-olefinshaving 3 to 10 carbon atoms, such as propylene, 1-butene, 1-pentene,1-hexene, 4-methyl- 1-pentene, 1-heptene and 1-octene, vinyl esters suchas vinyl acetate and vinyl propionate, unsaturated carboxylic acidesters such as methyl acrylate, ethyl acrylate, methyl methacrylate andethyl methacrylate, unsaturated compounds such as conjugated diene andnon-conjugated diene; and the like. The content of the ethylene unit inthe polyethylene resin may be 50% by mass or more based on the totalamount of monomer units.

The content of the thermoplastic resin may be 70% by mass or more or 75%by mass or more, and may be 85% by mass or less or 80% by mass or less,based on the total amount of the film, from the viewpoint of excellentproductivity. The content of the polyvinyl chloride resin, thepolyvinylidene chloride resin or the polyolefin resin is preferablywithin the above range, and the content of the polyvinyl chloride resin,the polyvinylidene chloride resin or the polyethylene resin is morepreferably within the above range.

The blue colorant is, for example, a colorant having a maximumabsorption wavelength in the visible light region (380 to 750 nm) of 600to 750 nm. The absorbance at the maximum absorption wavelength in thevisible light region of the blue colorant is preferably at least 2 timesand more preferably at least 3 times the absorbance at 470 nm.Specifically, the blue colorant may be copper phthalocyanine (copperphthalocyanine blue), iron(III) hexacyanoferrate(II),cobalt.oxide-aluminum oxide mixture, indigo, ultramarine, or the like.The blue colorant is preferably copper phthalocyanine from the viewpointof dispersibility.

The content of the blue colorant may be 0.5% by mass or more, and 2.0%by mass or less, based on the total amount of the film.

The polyglycerol fa acid ester is a compound represented by thefollowing formula (1).

In formula (1), R₁, R², and R³ each independently represent a hydrogenatom or a fatty acid residue (alkylcarbonyl group), and at least one ofR¹, R², and R³ represents a fatty acid residue (alkylcarbonyl group). Aportion of the fatty acid residue (alkylcarbonyl group) may besubstituted with a hydroxyl group or the like. The symbol n representsan integer of 3 or more. A plurality of R₂s may be the same as ordifferent from each other. These polyglycerol fatty acid esters may beused alone or in combination of two or more.

The number of carbon atoms of each residue of the fatty acidconstituting the polyglycerol fatty acid ester may be independently, forexample, 8 to 24. The residue of the fatty acid constituting thepolyglycerol fatty acid ester may be a saturated fatty acid or anunsaturated fatty acid. Examples of saturated fatty acids of the residueof the fatty acid constituting the polyglycerol fatty acid ester includecaprylic acid, pelargonic acid, capric acid, undecylic acid, lauricacid, tridecylic acid, myristylic acid, pentadecylic acid, palmiticacid, margaric acid, stearic acid, nonadecylic acid, arachidic acid,heneicosylic acid, behenic acid, tricosylic acid, and lignoceric acid.Examples of unsaturated fatty acids of the residue of the fatty acidconstituting the polyglycerol fatty acid ester include a-linolenic acid,stearidonic acid, eicosapentaenoic acid, docosapentaenoic acid,docosahexaenoic acid, linoleic acid, y-linolenic acid,dihomo-y-linolenic acid, arachidonic acid, docosapentaenoic acid,palmitoleic acid, vaccenic acid, bauric acid, oleic acid, elaidic acid,erucic acid, and nervonic acid. A part of these saturated fatty acidsand unsaturated fatty acids may be substituted with hydroxyl groups orthe like. Examples of compounds in which a part of the fatty acid issubstituted with a hydroxyl group include ricinoleic acid, linoleicacid, linolenic acid, sardine acid, and eleostearic acid.

The symbol n may be an integer from 3 to 20. The polyglycerol fatty acidester may be a mixture of two or more kinds of polyglycerol fatty acidesters each having a different n.

From the viewpoint of even better dispersibility of the blue colorant,the content of the polyglycerol fatty acid ester is preferably 0.5% bymass or more, more preferably 1.0% by mass or more, and furtherpreferably 1.5% by mass or more, based on the total amount of the film.The content of the polyglycerol fatty acid ester may be 2.5% by mass orless, or 2.0% by mass or less, based on the total amount of the film.

In addition to the thermoplastic resin, the blue colorant, and thepolyglycerol fatty acid ester, the film may further contain othercomponents. Examples of other components include a thermal stabilizer, alight stabilizer, an anti-fogging agent other than the polyglycerolfatty acid ester, a lubricant, a filler, a plate-out inhibitor, anantioxidant, a release agent, a viscosity lowering agent, a surfactant,a coloring agent other than the blue colorant, a fluorescent agent, asurface treatment agent, a crosslinking agent, a processing aid, apressure-sensitive adhesive, an antistatic agent, an ultravioletabsorber, an antiblocking agent, and the like.

The film may consist of a single layer containing the thermoplasticresin, the blue colorant and the polyglycerol fatty acid ester, or mayconsist of a plurality of layers. When the film consists of a pluralityof layers, the film may include, for example, a first surface layer, anintermediate layer and a second surface layer in this order. In thiscase, for example, the first and second surface layer may contain thethermoplastic resin and the polyglycerol fatty acid ester, and theintermediate layer may contain the blue colorant. The film may furtherincludes, for example, an adhesive layer containing an acid-modifiedpolyolefin resin or the like in order to improve the adhesion betweenlayers, and a heat resistant layer containing a polyamide resin may befurther provided in order to improve the heat resistance of the film.When the thermoplastic resin is a polyvinyl chloride resin, the filmpreferably consists of a single layer containing a thermoplastic resin(polyvinyl chloride resin), the blue colorant and the polyglycerin fattyacid ester.

The thickness of the film may be preferably 5 μm or more and morepreferably 6 μm or more, from the viewpoint of efficiently shielding thefood from the outside air, and may be preferably 25 μm or less and morepreferably 12 μm or less, from the viewpoint of excellent handlingproperty.

The film is produced by mixing a composition containing a thermoplasticresin, a blue colorant and a polyglycerol fatty acid ester with a mixersuch as a V-type blender, a ribbon blender, a Henschel mixer or a supermixer, and further kneading the mixture with a mixing roll, a Banburymixer or a kneading machine such as a kneader, as necessary, to obtain acomposition, followed by extrusion molding, for example. Specifically,the composition is supplied to a hopper of an extruder, and a targetedfilm is obtained by an inflation method, a T-die method, or the like.Generally, the film is wound while the film is being produced, and thewound film is further rewound (rolled) for each desired length such as20 m or 50 m, packed in a box (decorative box), thereby forming aproduct. That is, the film in this embodiment may be in the form of afood wrapping rolled film or in the form of a food wrapping rolled filmwith a box.

Specifically, as shown in FIG. 1, an article (a food wrapping rolledfilm) 1 with a box includes a food wrapping film 2, a core material 3 onwhich the food wrapping film 2 is rolled, and a box 4 in which the foodwrapping film 2 and the core material 3 are stored, and the box 4 may beprovided with a blade part 5 for cutting the food wrapping film 2. Thematerial of the core material 3 and the box 4 is not particularlylimited. From the viewpoint of easily recognizing the color of the film2 from the outside, at least a part of the box 4 is preferablytransparent, or has a hole in such a degree as not to impair thefunction as a box.

When the film is composed of a plurality of layers, the film can beobtained by putting the constituent raw materials of each layer intoseparate extruders, melt-extruding them, co-extruding each layer byinflation, T-die method or the like and laminating them. In this case,it is preferable to form the film by directly drawing the moltensubstance extruded from the T-die while rapidly cooling it with acasting roll or the like.

For the film obtained as above, depending on the purpose such asreduction in thermal shrinkage, natural shrinkage, etc. and suppressionof occurrence of width contraction, longitudinal stretching betweenheating rolls, various heat setting, or heat treatment such as aging maybe carried out. For the purpose of imparting and promoting anti-foggingproperty, antistatic property, tackiness, etc., surface treatment andsurface processing such as treatment such as corona treatment andripening, printing and coating and the like may be carried out.

The film described above is a film through which a wrapped food isvisually recognizable from the outside. Further, the film is a film(stretch film) having stretchability (extendablility).

The film according to the present embodiment may be a sorting film forfoods used for sorting foods. When using the film according to thepresent embodiment, two or more types of foods can be sorted into atleast two groups according to the type of food. That is, for example,the first food can be wrapped in the film according to the presentembodiment and sorted into the first group, while the second food can bewrapped in a film having a color different from that of the filmaccording to the present embodiment or a colorless film and sorted intothe second group.

Specifically, for example, when there is a first food containing a firstallergic substance and a second food containing a second allergicsubstance, the first food is sorted into a first group that is a groupof foods to be provided to a person having no allergic symptom with thefirst allergic substance, while the second food is sorted into a secondgroup that is a group of foods to be provided to a person having noallergic symptom with the second allergic substance. In the aboveexample, occurrence of an accident that the first or second allergicsubstance is provided to a person having an allergic symptom to theallergic substance can be suppressed.

EXAMPLES

Hereinafter, the present invention will be more specifically describedbased on examples, but the present invention is not limited to theexamples.

After charging the thermoplastic resin, blue colorant, anti-foggingagents, and various additives shown in Tables 1 and 2 into a supermixer, the material temperature was raised from normal temperature to130° C. while stirring the mixture. After mixing, the mixture was takenout when cooled down to 70° C. to prepare a resin composition. Eachresin composition was extruded at a resin temperature of 200° C. with aΦ 40 mm single screw extruder (L/D=20) equipped with a T-die (width 350mm, gap 0.4 mm) to prepare a film having a thickness of 8 μm. Thenumerical values in the tables are values in terms of solid content andrepresent % by mass.

Thermoplastic resin al: Polyvinyl chloride resin (“TH-1000” manufacturedby TAIYO VINYL CORPORATION, average degree of polymerization: 1000)

Thermoplastic resin a2: Polyethylene resin (“Neozex 0234N” manufacturedby Prime Polymer Co., Ltd.)

Blue colorant b 1: Copper phthalocyanine (copper phthalocyanine blue,“NX-053 blue” manufactured by Dainichiseika Color & Chemicals Mfg. Co.,Ltd.)

Anti-fogging agent c1: Polyglycerol fatty acid ester “POEM PR-300”manufactured by RIKEN VITAMIN Co., Ltd., polyglycerol polyricinoleate,mixture in which n in formula (1) is 4 to 6)

Anti-fogging agent c2: Diglycerol fatty acid ester (“O-71-DE”manufactured by RIKEN VITAMIN Co., Ltd., diglycerol oleate)

Anti-fogging agent c3: Glycerol fatty acid ester (“XO-100” manufacturedby RIKEN VITAMIN Co., Ltd., glycerin monooleate)

Anti-fogging agent c4: Sorbitan fatty acid ester (“L-250A” manufacturedby RIKEN VITAMIN Co., Ltd., sorbitan laurate)

Additive d1: Dioctyl adipate (“SANSO CIZER DOA” manufactured by NewJapan Chemical Co., Ltd.)

Additive d2: Epoxidized soybean oil (“Chemicizer SE-100” manufactured bySanwa Synthetic Chemical Industry Co., Ltd.)

Additive d3: Ca/Zn Stabilizer (“SC-308E” manufactured by ADEKACorporation)

(Evaluation of Dispersibility)

Each obtained film was cut into a 20 cm by 20 cm test piece.

Dispersibility of the blue colorant was evaluated by visually observingthe test piece for presence of shading. The evaluation criteria are asshown below. Dispersibility is good if the evaluation is A, B, or C.

A: No shading on test piece

B: Shading in one area of test piece

C: Shading in two or three areas of test piece

D: Shading in four areas or more of test piece

TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6Example 7 Composition a1 75.0 75.0 75.0 75.0 75.0 — — (% by mass) a2 — —— — — 97.0 98.3 b1 1.0 1.0 1.0 1.0 1.0 1.0 1.0 c1 2.0 1.0 1.0 1.0 0.52.0 0.5 c2 — 1.0 — — 0.1 — 0.1 c3 — — 1.0 — 0.1 — 0.1 c4 — — — 1.0 — — —d1 12.0 12.0 12.0 12.0 12.0 — — d2 9.0 9.0 9.0 9.0 10.3 — — d3 1.0 1.01.0 1.0 1.0 — — Dispersibility A B B B C B C

TABLE 2 Com- Com- Com- Com- parative parative parative parative Exam-Exam- Exam- Exam- ple 1 ple 2 ple 3 ple 4 Composition a1 75.0  77.0 77.0  — (% by mass) a2 — — — 98.0  b1 1.0 1.0 1.0 1.0 c1 — — — — c2 0.4— — 0.5 c3 0.4 0.6 — 0.5 c4 0.2 0.6 2.0 — d1 12.0  10.0  10.0  — d210.0  10.0  9.0 — d3 1.0 1.0 1.0 — Dispersibility D D D D

REFERENCE SIGNS LIST

1 . . . food wrapping rolled film with a box, 2 . . . food wrappingfilm, 3 . . . core material, 4 . . . box, 5 . . . blade part.

1. A food wrapping film comprising: a thermoplastic resin; a bluecolorant; and a polyglycerol fatty acid ester.
 2. The food wrapping filmaccording to claim 1, wherein a content of the polyglycerol fatty acidester is 0.5% by mass or more based on a total amount of the film. 3.The food wrapping film according to claim 1, wherein the thermoplasticresin is at least one selected from the group consisting of polyvinylchloride resins, polyvinylidene chloride resins, polyolefin resins,polystyrene resins, polyester resins and polyamide resins.
 4. The foodwrapping film according to claim 1, comprising, as the thermoplasticresin, 70% by mass or more based on the total amount of the film of atleast one resin selected from the group consisting of polyvinyl chlorideresins, polyvinylidene chloride resins and polyolefin resins.
 5. Anarticle comprising: the food wrapping film according to claim 1; a corematerial on which the food wrapping film is rolled; and a box in whichthe food wrapping film and the core material are stored, wherein the boxis provided with a blade part for cutting the food wrapping film.